Adhesive for bonding circuit members, circuit board and process for its production

ABSTRACT

An adhesive for bonding and securing a semiconductor chip to a circuit board and electrically connecting the electrodes of the two, and containing an adhesive resin composition and an inorganic filler being contained in an amount of 10 to 200 parts by weight of 100 parts by weight of the adhesive resin composition.

This application is a Divisional application of application Ser. No.12/549,909, filed Aug. 28, 2009 now abandoned, which is a Divisionalapplication of application Ser. No. 11/702,552, filed Feb. 6, 2007 nowU.S. Pat. No. 7,879,445, which is a Divisional application ofapplication Ser. No. 09/762,823, filed Apr. 23, 2001 now U.S. Pat. No.7,247,381, which is a National Stage Application filed under 35 USC 371of International (PCT) Application No. PCT/JP98/03609, filed Aug. 13,1998. The contents of application Ser. No. 09/762,823, filed Apr. 23,2001, are incorporated herein by reference in their entirety.

TECHNICAL FIELD

This invention relates to an adhesive for bonding circuit members whichis used to bond and fix a semiconductor chip to a substrate by, e.g.,flip-chip mounting and also to electrically interconnect electrodes ofthe both. It also relates to a circuit board having circuit membersbonded to one another, and a process for producing the circuit board.

BACKGROUND ART

In the field of semiconductor mounting, flip-chip mounting by which IC(integrated circuits) are directly mounted on a printed substrate or aflexible wiring board attracts notice as a new mounting form adaptableto achievement of lower cost and higher precision.

As methods for such flip-chip mounting, known are a method in whichsolder bumps are provided at terminals of a chip to effect solderbonding and a method in which electrical interconnection is made via aconductive adhesive. These methods have a problem that a stress due to adifference in coefficient of thermal expansion between the chip and thesubstrate that are to be bonded to each other may be generated to lowerconnection reliability when products are exposed to environment ofvarious types. Accordingly, a method has come to be commonly studied inwhich an underfill material of an epoxy resin type is injected into achip-/substrate gap in order to relax the stress at the bondinginterface.

There, however, is another problem that the step of injecting such anunderfill makes a process complicate to bring about a disadvantage inview of productivity and cost. To solve such a problem, what recentlyattracts notice from the viewpoint of process simplicity is flip-chipmounting that makes use of an anisotropic conductive adhesive havingboth anisotropic conductivity and encapsulation function.

However, where a chip is directly mounted on a substrate via theanisotropic conductive adhesive, the stress due to a difference incoefficient of thermal expansion between the chip and the substrate maybe generated in a temperature cycle test. This brings about a problemthat the adhesive may cause an increase in connection resistance orseparation at adhesive layers when reliability tests such as a thermalshock test, a PCT (pressure cooker test) and a solder bath immersiontest are made. Also, where projected electrodes are formed at connectingterminals of a chip, there is a problem that the stress due to adifference in coefficient of thermal expansion between the chip and thesubstrate may concentrate at the interface between the projectedelectrodes and the chip in the reliability tests, making the projectedelectrodes separate from their interface with chip electrodes to causefaulty conduction.

DISCLOSURE OF THE INVENTION

The present invention provides an adhesive for bonding circuit membersthat does hardly cause any increase in connection resistance orseparation at adhesive layers to bring about a great improvement inconnection reliability, and provides a circuit board having circuitmembers bonded to one another, and a process for producing the circuitboard.

A first adhesive for bonding circuit members according to the presentinvention is an adhesive for bonding circuit members which is to be putbetween circuit electrodes facing each other; the circuit electrodesfacing each other being pressed interposing the adhesive between them,to interconnect the electrodes electrically in the direction ofpressing;

the adhesive comprising an adhesive resin composition and an inorganicfiller; the inorganic filler being contained in an amount of from 10 to200 parts by weight based on 100 parts by weight of the adhesive resincomposition.

A second adhesive for bonding circuit members according to the presentinvention is an adhesive for bonding circuit members which is to be putbetween circuit electrodes facing each other; the circuit electrodesfacing each other being pressed interposing the adhesive between them,to interconnect the electrodes electrically in the direction ofpressing;

the adhesive being in multi-layer constitution having a first adhesivelayer comprising an adhesive resin composition and an inorganic fillerand containing the inorganic filler in an amount of from 10 to 200 partsby weight based on 100 parts by weight of the adhesive resincomposition, and a second adhesive layer containing an adhesive resincomposition as a main ingredient.

A third adhesive for bonding circuit members according to the presentinvention is an adhesive for bonding circuit members which is to be putbetween circuit electrodes facing each other; the circuit electrodesfacing each other being pressed interposing the adhesive between them,to interconnect the electrodes electrically in the direction ofpressing;

the adhesive comprising an adhesive resin composition and an inorganicfiller and having an average coefficient of thermal expansion of 200ppm/° C. or below at 110 to 130° C. after curing. It may preferably havean average coefficient of thermal expansion of from 30 to 200 ppm/° C.at 110 to 130° C. after curing.

A fourth adhesive for bonding circuit members according to the presentinvention is an adhesive for bonding circuit members which is to be putbetween circuit electrodes facing each other; the circuit electrodesfacing each other being pressed interposing the adhesive between them,to interconnect the electrodes electrically in the direction ofpressing;

the adhesive being in multi-layer constitution having a third adhesivelayer and a fourth adhesive layer which have physical propertiesdifferent in value from each other.

The above adhesive may preferably have a modulus of elasticity aftercuring which is higher in the third adhesive layer than in the fourthadhesive layer, and the fourth adhesive layer has a modulus ofelasticity of from 100 to 2,000 MPa at 40° C. after curing.

The adhesive may also preferably have a coefficient of thermal expansionwhich is smaller in the third adhesive layer than in the fourth adhesivelayer, and the third adhesive layer has a coefficient of thermalexpansion at 30 to 100° C., of from 20 to 70 ppm/° C.

The adhesive may preferably have a glass transition temperature that ishigher in the third adhesive layer than in the fourth adhesive layer,and the third adhesive layer has a glass transition temperature of 120°C. or above.

At least one layer of the third and fourth adhesive layers may containthe inorganic filler in an amount of from 10 to 200 parts by weightbased on 100 parts by weight of the adhesive resin composition.

The adhesive may contain conductive particles in an amount of from 0.1to 30 parts by volume based on 100 parts by volume of the adhesive resincomposition.

The adhesive may preferably have a modulus of elasticity of from 30 to2,000 MPa at 40° C. after the curing of the adhesive resin composition.

The adhesive resin composition may contain an epoxy resin, an acrylicrubber and a latent curing agent. The acrylic rubber may preferably bean acrylic rubber containing a glycidyl ether group in its molecule.

The adhesive may have the form of a film.

The circuit board of the present invention comprises;

a first circuit member having first connecting terminals; and

a second circuit member having second connecting terminals;

the first connecting terminal and the second connecting terminal beingdisposed facing each other, and an adhesive being put between the firstconnecting terminal and the second connecting terminal which aredisposed facing each other; and

the first connecting terminal and the second connecting terminaldisposed facing each other being electrically interconnected by pressingwith heating;

the adhesive being the adhesive for bonding circuit members according tothe present invention.

Where the first circuit member having first connecting terminals is aninorganic insulating substrate having first connecting terminals and thesecond circuit member having second connecting terminals is an organicinsulating substrate having second'connecting terminals, the firstadhesive layer or the third adhesive layer of the adhesive havingmulti-layer constitution stands adhered on the side of the first circuitmember.

The adhesive for bonding circuit members according to the presentinvention is an adhesive for bonding circuit members which is to be putbetween circuit electrodes facing each other; the circuit electrodesfacing each other being pressed interposing the adhesive between them,to interconnect the electrodes electrically in the direction ofpressing;

the adhesive comprising an adhesive resin composition and an inorganicfiller; the inorganic filler being contained in an amount of from 10 to200 parts by weight based on 100 parts by weight of the adhesive resincomposition; or

the adhesive being in multi-layer constitution having a first adhesivelayer containing the inorganic filler in an amount of from 10 to 200parts by weight based on 100 parts by weight of the adhesive resincomposition and a second adhesive layer containing an adhesive resincomposition as a major constituent. In such an adhesive for bondingcircuit members according to the present invention, in which theinorganic filler is contained in an amount of from 10 to 200 parts byweight based on 100 parts by weight of the adhesive resin composition,the adhesive resin composition may preferably be a composition having amodulus of elasticity of from 30 to 2,000 MPa at 40° C. after curing.Here, the adhesive may have a modulus of elasticity at 40° C. of from100 to 5,000 MPa, and preferably higher than 2,000 MPa and not higherthan 3,500 MPa.

An adhesive containing the adhesive resin composition having a modulusof elasticity of from 30 to 2,000 MPa at 40° C. after curing andcontaining the inorganic filler to have a modulus of elasticity at 40°C. which is higher than 2,000 MPa can relax its stress on account of theadhesive resin composition having a low modulus of elasticity and alsocan make its coefficient of thermal expansion small on account of theinorganic filler, making it possible to provide an adhesive for bondingcircuit members which has a superior connection reliability.

The second adhesive layer containing an adhesive resin composition as amain ingredient may preferably contain no inorganic filler. However, inorder to control properties, it may contain the inorganic filler in anamount smaller than that in the first adhesive layer, e.g. , less than50% by weight, and preferably less than 20% by weight.

The second adhesive layer containing an adhesive resin composition as amain ingredient may be an adhesive layer having a modulus of elasticityat 40° C. of from 100 to 2,000 MPa.

The adhesive having multi-layer constitution as used in the presentinvention may preferably be provided in accordance with the magnitude ofthe modulus of elasticity or coefficient of thermal expansion of circuitmembers to be bonded to each other. More specifically, the adhesive maypreferably be so provided that the third adhesive layer side havingrelatively a higher modulus of elasticity or smaller coefficient ofthermal expansion or higher glass transition temperature is applied onthe side of a circuit member having relatively a higher modulus ofelasticity or smaller coefficient of thermal expansion, and the fourthadhesive layer side having relatively a lower modulus of elasticity orlarger coefficient of thermal expansion or lower glass transitiontemperature is applied on the side of a circuit member having relativelya lower modulus of elasticity or larger coefficient of thermalexpansion.

In the adhesive having multi-layer constitution as used in the presentinvention, when, e.g., a semiconductor chip and an organic insulatingsubstrate are bonded to each other, the fourth adhesive layer,constituting the face on the side of the organic insulating substrate,may preferably have a modulus of elasticity of from 100 to 2,000 MPa at40° C. after curing, for the purpose of relieving the stress due to adifference in coefficient of thermal expansion between the chip and theorganic insulating substrate. The third adhesive layer, constituting theface on the side of the semiconductor chip, may have a modulus ofelasticity of from 500 to 5,000 MPa at 40° C. after curing, which ishigher than that of the fourth adhesive layer.

For the purpose of relieving the stress due to a difference incoefficient of thermal expansion between the chip and the organicinsulating substrate, the third adhesive layer constituting the face onthe side of the semiconductor chip may preferably have a coefficient ofthermal expansion at 30 to 100° C., of from 20 to 70 ppm/° C., and thefourth adhesive layer constituting the face on the side of the organicinsulating substrate may preferably have a coefficient of thermalexpansion at 30 to 100° C., of from 30 to 100 ppm/° C., which is largerthan that of the third adhesive layer.

For the purpose of relieving the stress due to a difference incoefficient of thermal expansion between the chip and the organicinsulating substrate, the third adhesive layer constituting the face onthe side of the semiconductor chip may preferably have a glasstransition temperature of 120° C. or higher and also 180° C. or lower,and the fourth adhesive layer constituting the face on the side of theorganic insulating substrate may preferably have a glass transitiontemperature lower than that of the third adhesive layer.

At least one layer of the third and fourth adhesive layers may containthe inorganic filler.

The coefficient of thermal expansion and glass transition temperature ofan adhesive film cured product corresponding to a stage after theadhesive has been applied may be measured with, e.g., a thermomechanicaltester TM-7000 (tensile mode; load: 5 gf; heating rate: 5° C./minute),manufactured by Shinku-Riko Inc. Here,.the adhesive film is cured underthe same conditions as heating temperature and time in the step ofbonding. The curing of the adhesive film may be effected by immersing itin an oil bath. Such an adhesive film cured product is a product inwhich 90% or more of heat of the total curing exotherm has beenliberated in the measurement with a DSC (differential scanningcalorimeter).

As the adhesive resin composition used in the present invention, usableis a mixture of an epoxy resin with any of latent curing agents such asimidazole types, hydrazide types, boron trifluoride-amine complexes,sulfonium salts, amine-imides, polyamine salts and dicyandiamide. Inorder to relax the stress due to a difference in coefficient of thermalexpansion between circuit members, preferred is an adhesive resincomposition having a modulus of elasticity of from 30 to 2,000 MPa at40° C. after curing.

For example, as an adhesive resin composition that can achieve good flowproperties and high connection reliability at the time of bonding,preferred are those prepared by mixing an acrylic rubber in the mixtureof an epoxy resin with any of latent curing agents such as imidazoletypes, hydrazide types, boron trifluoride-amine complexes, sulfoniumsalts, amine-imides, polyamine salts and dicyandiamide, so mixing themas to provide the modulus of elasticity of from 30 to 2,000 MPa at 40°C. after curing.

The modulus of elasticity of an adhesive resin composition cured productcorresponding to a stage after the adhesive resin composition has beenapplied may be measured by the DVE method using, e.g., RHEOSPECTRA DVE-4(tensile mode; frequency: 10 Hz; heating rate: 5° C./minute; measured at−40° C. up to 250° C.), manufactured by Rheology Co.). Here, theadhesive resin composition is cured under the same conditions as heatingtemperature and time in the step of bonding. The curing of the adhesiveresin composition film may be effected by immersing it in an oil bath.Such an adhesive resin composition film cured product is a product inwhich 90% or more of heat of the total curing exotherm has beenliberated in the measurement with the DSC.

The epoxy resin may include bisphenol type epoxy resins derived fromepichlorohydrin and bisphenol A, F, AD or the like; epoxy novolak resinsderived from epichlorohydrin and phenol novolak or cresol novolak;naphthalene type epoxy resins having a skeleton containing a naphthalenering; and epoxy compounds having at least two glycidyl groups in themolecule, such as glycidyl amine, glycidyl ether, biphenyl andalicyclics; any of which may be used alone or in combination of two ormore types. As these epoxy resins, in order to prevent electronmigration it is preferable to use high-purity products in which impurityions (such as Na⁺ and Cl⁻), hydrolyzable chlorine and so forth have beenreduced to 300 ppm or less.

The epoxy resin may preferably be a trifunctional or higherpolyfunctional epoxy resin and/or a naphthalene type epoxy resin inorder to ensure a low coefficient of thermal expansion and a high glasstransition temperature. The trifunctional or higher polyfunctional epoxyresin may include phenol novolak type epoxy resins, cresol novolak typeepoxy resins, trishydroxyphenylmethane type epoxy resins,tetraphenylolethane type epoxy resins, and dicycloropentadiene phenoltype epoxy resins. In addition, the naphthalene type epoxy resin has astructure containing at least one naphthalene ring in one molecule, andmay include naphthol types and naphthalenediol types.

The acrylic rubber may include polymers or copolymers having as amonomer component at least one of acrylic acid, acrylate, methacrylateand acrylonitrile. In particular, copolymer type acrylic rubberscontaining glycidyl acrylate or glycidyl methacrylate having a glycidylether group may preferably be used.

These acrylic rubbers may preferably be those having a molecular weightof 200,000 or more in view of improvement in cohesive force of theadhesive resin composition. If the acrylic rubber is mixed in an amountnot more than 15% by weight in the adhesive resin composition, thecomposition may have a modulus of elasticity higher than 2,000 MPa at40° C. after curing. If on the other hand it is in an amount more than40% by weight, though a low modulus of elasticity is achievable, thecomposition may have so high a melt viscosity at the time of bondingthat the molten adhesive may be low removable at the interface to makeit impossible to ensure electrical conduction between electrodesinterconnected or between electrodes interconnected and conductiveparticles. Accordingly, the acrylic rubber may preferably be mixed in anamount of from 15 to 40% by weight. These acrylic rubbers mixed in theadhesive resin composition have a peak temperature at about 40 to 60°C., of dielectric dissipation factor due to the rubber component, andhence the adhesive composition can be made to have a low modulus ofelasticity.

The adhesive resin composition may preferably have a modulus ofelasticity of from 30 to 2,000 MPa at 40° C. after curing. The adhesivemay have a modulus of elasticity of from 100 to 5,000 MPa at 40° C.after curing, and may have one higher than 2,000.

A thermoplastic resin such as a phenoxy resin may also be mixed in theadhesive in order to more improve film-forming properties. Inparticular, the phenoxy resin is preferred because it has characteristicfeatures that, e.g., it is structurally similar to the epoxy resin andhence has good compatibility with, and adhesion to, the epoxy resin. Toform film, an adhesive composition comprised of at least these epoxyresin, acrylic rubber, phenoxy resin and latent curing agent andconductive particles may be dissolved or dispersed in an organic solventto prepare a liquid material, which may then be coated on the surface ofa film-releasable substrate, followed by removal of the solvent at atemperature lower than the curing-agent activation temperature. Thesolvent used here may preferably be a mixed solvent of an aromatichydrocarbon type solvent and an oxygen-containing solvent in order toimprove solubility of materials.

The inorganic filler used in the present invention may include, but notparticularly limited to, e.g., powders of fused silica, crystallinesilica, calcium silicate, alumina, calcium carbonate and the like. Theinorganic filler may be mixed in an amount of from 10 to 200 parts byweight based on 100 parts by weight of the adhesive resin composition.The more the filler is mixed, the more effective it is to ensure a lowcoefficient of thermal expansion. However, its mixing in a largequantity may cause faulty conduction because the adhesive may have a lowadhesion or may be low removable at the bonding part. If it is mixed ina small quantity, any low coefficient of thermal expansion may beensured. Accordingly, it may preferably be mixed in an amount of from 20to 90 parts by weight. In addition, it may have an average particlediameter smaller than 3 μm so that any faulty conduction at the bondingpart can be prevented. In addition, for the purpose of preventing resinflowability from lowering and chip's passivation film from being damagedat the time of bonding, it is preferable to use a spherical filler.

In the adhesive of the present invention, conductive particles may bemixed and dispersed for the purpose of intentionally providinganisotropic conductivity in order to assimilate any uneven height'ofchip bumps or substrate electrodes. In the present invention, theconductive particles may be particles of metals as exemplified by Au,Ag, Cu and solder, and may preferably be those comprising spherical corematerials of polymers such as polystyrene provided thereon withconductive layers of Ni, Cu, Au, solder or the like. In addition,surface layers of Su, Au, solder or the like may be formed on thesurfaces of conductive particles. Such particles must have a particlediameter that is smaller than the minimum gap of substrate electrodes.Where the electrodes have uneven height, the particles may preferablyhave a particle diameter that is larger than the uneven height, andpreferably from 1 to 10 μM. In addition, the conductive particles may bedispersed in the adhesive in an amount of from 0.1 to 30 parts byvolume, and preferably from 0.2 to 15 parts by volume, based on 100parts by volume of the adhesive resin composition.

The adhesive of the present invention may be used as a film adhesive.

To obtain the film adhesive, an adhesive composition comprised of theepoxy resin, acrylic rubber, latent curing agent and so forth may bedissolved or dispersed in an organic solvent to prepare a liquidmaterial, which may then be coated on the surface of a film-releasablesubstrate, followed by removal of the solvent at a temperature lowerthan the curing-agent activation temperature.

A film adhesive having multi-layer constitution may be obtained by amethod in which a first or third film adhesive and a second or fourthfilm adhesive may individually be formed by coating on the surface of aseparator film (film-releasable substrate) comprised of polyethyleneterephthalate, fluorine type resin or the like and thereafter the firstor third film adhesive and the second or fourth film adhesive arelaminated by pressing or by pressing and simultaneously heating toobtain a film adhesive comprised of the first or third film adhesive andthe second or fourth film adhesive, or a method in which the first orthird film adhesive (or the second or fourth film adhesive) is formed onthe surface of the separator film and further thereon the second orfourth film adhesive (or the first or third film adhesive) issuperposingly formed by coating to obtain a film adhesive comprised ofthe first or third film adhesive and the second or fourth film adhesive.

The film adhesive obtained by lamination of the first or third filmadhesive and the second or fourth film adhesive may preferably be in athickness of from 20 to 120 μm in total. The first or third filmadhesive and the second or fourth film adhesive may individuallypreferably be in a thickness ratio in the range of first or third filmadhesive : second or fourth film adhesive=1:9 to 9:1. Especially whensemiconductor chips are bonded to an organic insulating substrate, theratio may preferably be in the range of first or third filmadhesive:second or fourth film adhesive=3:7 to 7:3.

The film adhesive may preferably have a layer thickness larger than thegap between the first and the second circuit members, and shouldcommonly have a layer thickness larger by at least 5 μm than the gap.

In the present invention, as the circuit members, usable are chipcomponent parts such as semiconductor chips, resistor chips andcapacitor chips, printed substrates, and flexible wiring boardscomprised of polyimide or polyester as a base material.

The chip component parts comprise a non-metallic inorganic insulatingsubstrate such as silicon, glass, ceramic or compound semiconductorsubstrate and formed thereon a large number of connecting terminals. Theprinted substrates and the flexible wiring boards comprised of polyimideor.polyester as a base material comprise an organic insulating substrateand formed thereon a large number of connecting terminals.

As a substrate on which the chip component parts are mounted, an organicinsulating substrate having electrodes (connecting terminals) formedcorrespondingly to semiconductor chip terminals may be used.

As the organic insulating substrate, usable are a synthetic-resin filmof polyimide resin, polyester resin or the like, and a laminated sheetobtained by impregnating a glass substrate such as glass cloth or glassnonwoven fabric with a resin such as polyimide resin, epoxy resin orphenol resin, followed by curing.

A multi-layer wiring board may be used which has electrodes to beconnected to chip terminals, a surface insulating layer having theseterminals formed thereon, a given number of insulating layers, a givennumber of wiring layers provided between the respective insulatinglayers, and holes having been made conductive through which theelectrodes and the wiring layers are electrically interconnected.

Such a multi-layer wiring board may preferably be a built-up multi-layersubstrate obtained by forming insulating layers and conductive circuitlayers alternately on the surface of a base material having aninsulating layer formed using glass cloth or on the surface of a wiringsubstrate having at least one conductor circuit.

As the surface insulating layer, a resin film may be used. As this resinfilm, usable are films of epoxy resins, polyimide resins,polyimide-imide resins, modified polyphenylene ether resins, phenoxyresins, amide-epoxy resins or phenolic resins, or mixtures, copolymersor the like of any of these; and films of heat-resistant thermoplasticengineering plastics such as polysulfone, polyether sulfone, polyetherether ketone, totally aromatic liquid-crystal polyesters, and fluorineresins. Resin films in which an organic or inorganic filler is containedmay be used. As insulating layers formed of resins reinforced with aglass base material, prepregs may be used which are obtained byimpregnating a glass substrate such as glass cloth or glass nonwovenfabric with a resin such as epoxy resin or phenol resin, followed bycuring.

The circuit members are provided with connecting terminals that areusually in a large number (or may be single in some cases). At least oneset of the circuit members is so disposed that at least some of theconnecting terminals provided on these circuit members face each other,and the adhesive is put between the connecting terminals disposed facingeach other, followed by pressing with heating to electricallyinterconnect the connecting terminals disposed facing each other, tomake up a circuit board.

At least one set of circuit members is pressed with heating, whereuponthe connecting terminals disposed facing each other are electricallyinterconnected by direct contact or via the conductive particles of theanisotropic conductive adhesive.

On electrode pads of the semiconductor chip or substrate, bumps formedby plating and tips of gold wires may be melted by means of a torch orthe like to form gold balls, and these balls may be contact-bonded ontothe electrode pads. Thereafter, projected electrodes such as wire bumpsobtained by cutting wires may be provided so as to be used as theconnecting terminals.

A process for producing the circuit board will be described taking thecase of an instance in which a first circuit member comprised of aninorganic insulating substrate and a second circuit member comprised ofan organic insulating substrate are bonded with a film adhesive.

A first circuit member comprised of an inorganic insulating substrate,having a first connecting terminal, and a second circuit membercomprised of an organic insulating substrate, having a second connectingterminal, are disposed in such a way that the first connecting terminaland the second connecting terminal face each other, which are sodisposed that the adhesive for bonding circuit members according to thepresent invention is put between the first connecting terminal and thesecond connecting terminal which have been disposed facing each other,in such a way that the first or third adhesive layer is on the side ofthe first circuit member, followed by pressing to electricallyinterconnect the first connecting terminal and the second connectingterminal disposed facing each other. Thus, the circuit board of thepresent invention can be produced.

Stated specifically, for example, firstly the surface of a film, secondor fourth adhesive layer is brought into contact with the second circuitmember to provisionally fix the film adhesive to the second circuitmember. Subsequently, the electrodes of the first circuit member areregistered on the electrodes of the second circuit member, where a loadof 20 to 150 gf per electrode is applied from the part on the side ofthe first circuit member, during which heat is so applied for 10 to 20seconds that the film adhesive is heated to 180 to 200° C. to cure thefilm adhesive. Thus, the electrodes of the first circuit member and theelectrodes of the second circuit member are electrically interconnectedand at the same time this state of connection between the first circuitmember and the second circuit member is retained on account of thecuring of the film adhesive.

An example in which a semiconductor chip is bonded to a mountingsubstrate will be described with reference to FIGS. 1 and 2. FIG. 1shows an example in which a semiconductor chip is bonded to a mountingsubstrate by means of an adhesive not containing any conductiveparticles. FIG. 2 shows a bonded portion where a semiconductor chip isbonded to a mounting substrate by means of an adhesive containingconductive particles.

An electronic component device shown in FIG. 1 is constituted of amounting substrate 20 and a semiconductor chip 10 mounted thereon.Incidentally, FIG. 1 shows part of the electronic component device.Actually, other component parts such as other semiconductor chips aremounted on the mounting substrate 20.

On the semiconductor chip 10, projected electrodes (bumps) serving asconnecting electrodes 11 are formed on its one face. The chip iselectrically interconnected to the mounting substrate via the connectingelectrodes 11.

The mounting substrate 20 has a plurality of insulating layers 21 and22, a plurality of wiring layers 32 and 33 disposed via the insulatinglayers 21 and 22, connecting electrode terminals 31 for makingconnection with the connecting electrodes 11 of the semiconductor chip10, and a conductor 34 provided through the insulating layers 21 and 22to electrically interconnect wiring layers specified among the wiringlayers 32 and 33. In order to pass the conductor 34 through theinsulating layers, the insulating layers 21 and 22 are provided, attheir necessary spots, with holes 25 for serving as through-holes. Morespecifically, this mounting substrate constitutes a resin composite typemulti-layer wiring board. Here, the wiring layers 32 are provided as aninner-layer circuit, and the wiring layers 33 are provided as anouter-layer circuit. The connecting electrode terminals 31 function as aconductor circuit on which the chip is to be mounted.

The projected electrodes (bumps) which are connecting electrodes 11provided on the semiconductor chip 10 are registered on the connectingelectrode terminals 31 provided on the surface of the mounting substrate20. A film adhesive 40 for bonding has been disposed between thesemiconductor chip 10 and the mounting substrate 20. In this state,pressure and heat are applied from the part on the side of thesemiconductor chip 10, whereby the adhesive 40 come to flow and thencure, so that the connecting electrodes 11 provided on the semiconductorchip 10 and the connecting electrode terminals 31 provided on thesurface of the mounting substrate 20 come into direct mechanical contactto attain electrical interconnection.

Where an adhesive 40 such as an anisotropic conductive adhesive havingconductive particles 41 is used, as shown in FIG. 2 the connectingelectrodes 11 are connected to the connecting electrode terminals 31 inthe state the conductive particles 41 are interposed between them, andsimultaneously bonded and fixed there. In the case when the anisotropicconductive adhesive 40 is used and in the state where electrode surfacesfacing each other to be bonded are brought into pressure contact, theconduction between the electrodes facing each other is effected via theconductive particles interposed between them. In addition, betweenadjacent electrodes, the adhesive, though containing conductiveparticles, has the conductive particles in a low density and henceexhibits no conductivity.

The mounting substrate 20 has at least one first insulating layer 21formed of a resin reinforced with a glass base material, and a secondinsulating layer 22 which constitutes one layer at least on the side onwhich the electronic component parts are bonded and fixed. Incidentally,in the example shown in FIG. 1, the second insulating layer 22 is alsoprovided on the side different from the side on which the electroniccomponent parts are bonded and fixed.

According to the adhesive of the present invention, any stress at theinterface between the semiconductor chip and the adhesive for bondingcircuit members can be relaxed, and besides, in the case when it has amodulus of elasticity of from 30 to 2,000 MPa at 40° C. as the adhesiveresin composition, the stress generated in reliability tests such as thethermal shock test, PCT or solder bath immersion test can also beabsorbed by the adhesive resin composition. Hence, the adhesive maycause neither increase in connection resistance at bonded portions norseparation at adhesive layers even after the reliability tests, bringingabout a great improvement in connection reliability. The presentinvention makes it possible to provide a gradation of physicalproperties in the thickness direction of the adhesive for bondingcircuit members, and hence the adhesive can absorb internal stressgenerated in the reliability tests such as the thermal shock test, PCTor solder bath immersion test. Thus, the adhesive may cause neitherincrease in connection resistance at bonded portions nor separation atadhesive layers even after the reliability tests, bringing about a greatimprovement in connection reliability. In addition, the film adhesive isconvenient to handle.

Accordingly, the adhesive of the present invention may preferably beused to make electrical connection between LCD (liquid-crystal display)panels and TAB (tape automated bonding) substrates, TAB substrates andflexible circuit substrates, LCD panels and IC chips, and IC chips andprinted wiring substrates only in the direction of pressing at the timeof bonding.

The circuit board of the present invention can absorb the stressgenerated in the reliability tests, and may cause neither increase inconnection resistance at bonded portions nor separation at adhesivelayers even after the reliability tests, bringing about a greatimprovement in connection reliability. In addition, in the circuit boardof the present invention, the film adhesive having a small coefficientof thermal expansion is used on the chip side and the stress generatedat the interface between the chip and the adhesive can be relaxed. Thus,when the projected electrodes are provided on electrode pads of thechip, any separation of the projected electrodes from the electrode padscan be made greatly less occur.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional illustration of an example of theconstruction of an electronic component device according to the presentinvention.

FIG. 2 is a cross-sectional illustration of an example of the state ofconnection between electronic component parts and a mounting substrate.

BEST MODES FOR PRACTICING THE INVENTION Example 1

50 g of phenoxy resin and 125 g of acrylic rubber (molecular weight:850,000) obtained by copolymerization of butyl acrylate (40 parts),ethyl acrylate (30 parts), acrylonitrile (30 parts) and glycidylmethacrylate (3 parts) were dissolved in 400 g of ethyl acetate toobtain a 30% solution.

Next, 325 g of liquid epoxy (epoxy equivalent weight: 185) containing amicrocapsular latent curing agent was added to this solution, followedby stirring, where fused silica (average particle diameter: 0.5 μm) inan amount of 40 parts by weight based on 100 parts by weight of theadhesive resin composition and also 2% by volume of nickel particles(diameter: 3 μm) were dispersed to obtain a film coating fluid.

This film coating fluid was coated on a separator (silicone-treatedpolyethylene terephthalate film; thickness: 40 μm) by means of a rollcoater, followed by drying at 100° C. for 10 minutes to form an adhesivefilm a of 45 μm thick. This adhesive film a had a modulus of elasticityat 40° C. of 800 MPa after curing as measured with a dynamicviscoelasticity measuring instrument on only an adhesive resincomposition from which the fused silica and nickel particles wereremoved.

Next, using the adhesive film a thus obtained, a chip (10 mm×10 mm;thickness: 0.5 mm) with gold bumps (area: 80 μm×80 μm each; space: 30μm; height: 15 μm; the number of bumps: 288) was bonded to aNi/Au-plated Cu circuit printed substrate in the manner as shown below.

First, the adhesive film a (12 mm×12 mm) was stuck to the Ni/Au-platedCu circuit printed substrate (electrode height: 20 μm; thickness: 0.8mm) at 80° C. and 10 kgf/cm². Thereafter, the separator was peeled, andthe bumps of the chip were registered on the Ni/Au-plated Cu circuitprinted substrate (thickness: 0.8 mm). Then, heat and pressure wereapplied from above the chip under conditions of 180° C., 30 g/bump and20 seconds to effect main bonding.

Connection resistance after the main bonding was 6 mΩ at maximum perbump and 2 mΩ on the average, and insulation resistance was 10⁸Ω orabove. These values did not change even after 1,000-cycle treatment in athermal shock test made at −55 to 125° C., after a PCT (121° C., 2atmospheric pressure) made for 200 hours, and after 260° C. solder bathimmersion for 10 seconds, showing good connection reliability.

Example 2

50 g of phenoxy resin and 175 g of acrylic rubber (molecular weight:850,000) obtained by copolymerization of butyl acrylate (40 parts),ethyl acrylate (30 parts), acrylonitrile (30 parts) and glycidylmethacrylate (3 parts) were dissolved in 525 g of ethyl acetate toobtain a 30% solution.

Next, 275 g of liquid epoxy (epoxy equivalent weight: 185) containing amicrocapsular latent curing agent was added to this solution, followedby stirring, where fused silica (average particle diameter: 0.5 μm) inan amount of 60 parts by weight based on 100 parts by weight of theadhesive resin composition and also 2% by volume of nickel particles(diameter: 5 μm) were dispersed to obtain a film coating fluid.

This film coating fluid was coated on a separator (silicone-treatedpolyethylene terephthalate film; thickness: 40 μm) by means of a rollcoater, followed by drying at 100° C. for 10 minutes to form an adhesivefilm b of 45 μm thick. This adhesive film b had a modulus of elasticityat 40° C. of 400 MPa after curing as measured with a dynamicviscoelasticity measuring instrument on only an adhesive resincomposition from which the fused silica and nickel particles wereremoved.

Next, using the adhesive film b thus obtained, a chip (10 mm×10 mm) withgold bumps (area: 80 μm×80 μm each; space: 30 μm; height: 15 μm; thenumber of bumps: 288) was bonded to a Ni/Au-plated Cu circuit printedsubstrate (electrode height: 20 μm; thickness: 0.8 mm) in the manner asshown below.

First, the adhesive film b (12 mm×12 mm) was stuck to the Ni/Au-platedCu circuit printed substrate at 80° C. and 10 kgf/cm². Thereafter, theseparator was peeled, and the bumps of the chip were registered on theNi/Au-plated Cu circuit printed substrate. Then, heat and pressure wereapplied from above the chip under conditions of 170° C., 30 g/bump and20 seconds to effect main bonding.

Connection resistance after the main bonding was 18 mΩ at maximum perbump and 8 mΩ on the average, and insulation resistance was 10⁸Ω orabove. These values did not change even after 1,000-cycle treatment in athermal shock test made at −55 to 125° C., after a PCT (121° C., 2atmospheric pressure) made for 200 hours, and after 260° C. solder bathimmersion for 10 seconds, showing good connection reliability.

Example 3

50 g of phenoxy resin and 100 g of acrylic rubber (molecular weight:850,000) obtained by copolymerization of butyl acrylate (40 parts),ethyl acrylate (30 parts), acrylonitrile (30 parts) and glycidylmethacrylate (3 parts) were dissolved in 350 g of ethyl acetate toobtain a 30% solution.

Next, 350 g of liquid epoxy (epoxy equivalent weight: 185) containing amicrocapsular latent curing agent was added to this solution, followedby stirring, where fused silica (average particle diameter: 0.5 μm) inan amount of 60 parts by weight based on 100 parts by weight of theadhesive resin composition and also 5% by volume of conductive particlesobtained by forming Au layers on polystyrene cores (diameter: 5 μm) weredispersed to obtain a film coating fluid.

This film coating fluid was coated on a separator (silicone-treatedpolyethylene terephthalate film; thickness: 40 μm) by means of a rollcoater, followed by drying at 100° C. for 10 minutes to form an adhesivefilm c of 45 μm thick. This adhesive film c had a modulus of elasticityat 40° C. of 1,000 MPa after curing as measured with a dynamicviscoelasticity measuring instrument on only an adhesive resincomposition from which the fused silica and nickel particles wereremoved.

Next, using the adhesive film c thus obtained, a chip (10 mm×10 mm;thickness: 0.5 mm) with gold bumps (area: 80 μm×80 μm each; space: 30μm; height: 15 μm; the number of bumps: 288) was bonded to aNi/Au-plated Cu circuit printed substrate (electrode height: 20 μm;thickness: 0.8 mm) in the manner as shown below.

First, the adhesive film c (12 mm×12 mm) was stuck to the Ni/Au-platedCu circuit printed substrate at 80° C. and 10 kgf/cm². Thereafter, theseparator was peeled, and the bumps of the chip were registered on theNi/Au-plated Cu circuit printed substrate. Then, heat and pressure wereapplied from above the chip under conditions of 170° C., 30 g/bump and20 seconds to effect main bonding.

Connection resistance after the main bonding was 5 mΩ at maximum perbump and 1.5 mΩ on the average, and insulation resistance was 10⁸Ω orabove. These values did not change even after 1,000-cycle treatment in athermal shock test made at −55 to 125° C., after a PCT (121° C., 2atmospheric pressure) made for 200 hours, and after 260° C. solder bathimmersion for 10 seconds, showing good connection reliability.

Example 4

50 g of phenoxy resin and 100 g of acrylic rubber (molecular weight:850,000) obtained by copolymerization of butyl acrylate (40 parts),ethyl acrylate (30 parts), acrylonitrile (30 parts) and glycidylmethacrylate (3 parts) were dissolved in 350 g of ethyl acetate toobtain a 30% solution.

Next, 350 g of liquid epoxy (epoxy equivalent weight: 185) containing amicrocapsular latent curing agent was added to this solution, followedby stirring, where fused silica (average particle diameter: 0.5 μm) inan amount of 40 parts by weight based on 100 parts by weight of theadhesive resin composition and also 5% by volume of conductive particlesobtained by forming Au layers on polystyrene cores (diameter: 5 μm) weredispersed to obtain a film coating fluid.

This film coating fluid was coated on a separator (silicone-treatedpolyethylene terephthalate film; thickness: 40 μm) by means of a rollcoater, followed by drying at 100° C. for 10 minutes to form an adhesivefilm d of 45 μm thick. This adhesive film d had a modulus of elasticityat 40° C. of 1,000 MPa after curing as measured with a dynamicviscoelasticity measuring instrument on only an adhesive resincomposition from which the fused silica and nickel particles wereremoved. In-addition, the adhesive film d had an average coefficient ofthermal expansion at 110 to 130° C. of 111 ppm as measured by the TMAmethod.

Next, using the adhesive film d thus obtained, a chip (1.7 mm×17 mm;thickness: 0.5 mm) with gold bumps (area: 50 μm×50 μm each; 362 bumps;space: 20 μm; height: 15 μm) was bonded to a glass substrate (thickness:1.1 mm) with an ITO (yttrium tin oxide) circuit in the manner as shownbelow.

First, the adhesive film c (12 mm×12 mm) was stuck to the glasssubstrate with an ITO circuit at 80° C. and 10 kgf/cm². Thereafter, theseparator was peeled, and the bumps of the chip were registered on theglass substrate with an ITO circuit. Then, heat and pressure wereapplied from above the chip under conditions of 180° C., 40 g/bump and20 seconds to effect main bonding.

Connection resistance after the main bonding was 150 mΩ at maximum perbump and 80 mΩ on the average, and insulation resistance was 10⁸Ω orabove. These values did not change even after 1,000-cycle treatment in athermal shock test made at −40 to 100° C. and after a PCT (105° C., 1.2atmospheric pressure) made for 100 hours, showing good connectionreliability.

Example 5

50 g of phenoxy resin and 125 g of acrylic rubber (molecular weight:850,000) obtained by copolymerization of butyl acrylate (40 parts),ethyl acrylate (30 parts), acrylonitrile (30 parts) and glycidylmethacrylate (3 parts) were dissolved in 400 g of ethyl acetate toobtain a 30% solution.

Next, 325 g of liquid epoxy (epoxy equivalent weight: 185) containing amicrocapsular latent curing agent was added to this solution, followedby stirring, where fused silica (average particle diameter: 0.5 μm) inan amount of 60 parts by weight based on 100 parts by weight of theadhesive resin composition and also 2% by volume of nickel particles(diameter: 5 μm) were dispersed to obtain a film coating fluid.

This film coating fluid was coated on a separator (silicone-treatedpolyethylene terephthalate film; thickness: 40 μm) by means of a rollcoater, followed by drying at 100° C. for 10 minutes to form an adhesivefilm e of 45 μm thick. This adhesive film e had a modulus of elasticityat 40° C. of 800 MPa after curing as measured with a dynamicviscoelasticity measuring instrument on only an adhesive resincomposition from which the fused silica and nickel particles wereremoved.

Next, using the adhesive film e thus obtained, a bumpless chip (10 mm×10mm; thickness: 0.5 mm; pad electrode: Al; pad diameter: 120 μm) wasbonded to a Ni/Au-plated Cu circuit printed substrate on the circuit ofwhich Ni/Au-plated Cu bumps (diameter: 100 μm; space: 50 μm; height: 15μm ; the number of bumps: 200) were formed, which was bonded in themanner as shown below.

First, the adhesive film e (12 mm×12 mm) was stuck to the Ni/Au-platedCu circuit printed substrate (electrode height: 20 μm; thickness: 0.8mm) at 80° C. and 10 kgf/cm². Thereafter, the separator was peeled, andthe Al pads of the chip were registered on the Ni/Au-plated Cu circuitprinted substrate (thickness: 0.8 mm) with Ni/Au-plated Cu bumps. Then,heat and pressure were applied from above the chip under conditions of180° C., 30 g/bump and 20 seconds to effect main bonding.

Connection resistance after the main bonding was 8 mΩ at maximum perbump and 4 mΩ on the average, and insulation resistance was 10⁸Ω orabove. These values did not change even after 1,000-cycle treatment in athermal shock test made at −55 to 125° C., after a PCT (121° C., 2atmospheric pressure) made for 200 hours, and after 260° C. solder bathimmersion for 10 seconds, showing good connection reliability.

Example 6

50 g of phenoxy resin and 125 g of acrylic rubber (molecular weight:850,000) obtained by copolymerization of butyl acrylate (40 parts),ethyl acrylate (30 parts), acrylonitrile (30 parts) and glycidylmethacrylate (3 parts) were dissolved in 400 g of ethyl acetate toobtain a 30% solution.

Next, 325 g of liquid epoxy (epoxy equivalent weight: 185) containing amicrocapsular latent curing agent was added to this solution, followedby stirring, where fused silica (average particle diameter: 0.5 μm) inan amount of 40 parts by weight based on 100 parts by weight of theadhesive resin composition was dispersed to obtain a film coating fluid.

This film coating fluid was coated on a separator (silicone-treatedpolyethylene terephthalate film; thickness: 40 μm) by means of a rollcoater, followed by drying at 100° C. for 10 minutes to forma firstadhesive layer, adhesive film f (thickness: 25 μm). This adhesive film fhad a modulus of elasticity at 40° C. of 800 MPa after curing asmeasured with a dynamic viscoelasticity measuring instrument on only anadhesive resin composition from which the fused silica was removed.

A second adhesive layer, adhesive film g (thickness: 25 μm) was alsoformed in the same manner as the formation of the adhesive film g exceptthat 2% by volume of nickel particles (diameter: 3 μm) were dispersed inplace of the dispersing of the fused silica. The resultant adhesive filmg had a modulus of elasticity at 40° C. of 800 MPa.

Next, the adhesive film f and adhesive film g thus obtained werelaminated to obtain a composite film, laminated film adhesive h.

Using this laminated film adhesive h, a chip (10 mm×10 mm; thickness:0.5 mm) with gold bumps (area: 80 μm×80 μm each; space: 30 μm; height:15 μm; the number of bumps: 288) was bonded to a Ni/Au-plated Cu circuitprinted substrate in the manner as shown below.

First, the adhesive film g (second adhesive layer) of this laminatedfilm adhesive h (12 mm×12 mm) was stuck to the Ni/Au-plated Cu circuitprinted substrate (electrode height: 20 μm; thickness: 0.8 mm) at 80° C.and 10 kgf/cm². Thereafter, the separator was peeled, and the chip wasfaced on the side of the adhesive film f (first adhesive layer), wherethe bumps of the chip were registered on the Ni/Au-plated Cu circuitprinted substrate (thickness: 0.8 mm). Then, heat and pressure wereapplied from above the chip under conditions of 180° C., 50 g/bump and20 seconds to effect main bonding.

Connection resistance after the main bonding was 6 mΩ at maximum perbump and 2 mΩ on the average, and insulation resistance was 10⁸Ω orabove. These values did not change even after 1,000-cycle treatment in athermal shock test made at −55 to 125° C., after a PCT (121° C., 2atmospheric pressure) made for 200 hours, and after 260° C. solder bathimmersion for 10 seconds, showing good connection reliability.

Example 7

50 g of phenoxy resin and 175 g of acrylic rubber (molecular weight:850,000) obtained by copolymerization of butyl acrylate (40 parts),ethyl acrylate (30 parts), acrylonitrile (30 parts) and glycidylmethacrylate (3 parts) were dissolved in 525 g of ethyl acetate toobtain a 30% solution.

Next, 275 g of liquid epoxy (epoxy equivalent weight: 185) containing amicrocapsular latent curing agent was added to this solution, followedby stirring, where fused silica (average particle diameter: 1 μm) in anamount of 60 parts by weight based on 100 parts by weight of theadhesive resin composition was dispersed to obtain a film coating fluid.

This film coating fluid was coated on a separator (silicone-treatedpolyethylene terephthalate film; thickness: 40 μm) by means of a rollcoater, followed by drying at 100° C. for 10 minutes to form an adhesivefilm i (thickness: 20 μm) corresponding to the first adhesive layer.This adhesive film i had a modulus of elasticity at 40° C. of 400 MPaafter curing as measured with a dynamic viscoelasticity measuringinstrument on only an adhesive resin composition from which the fusedsilica was removed.

An adhesive film j (thickness: 20 μm) corresponding to the secondadhesive layer was also formed in the same manner as the formation ofthe adhesive film i except that 2% by volume of nickel particles(diameter: 5 μm) were dispersed in place of the dispersing of the fusedsilica. The resultant adhesive film j had a modulus of elasticity at 40°C. of 400 MPa.

Next, the adhesive film i and adhesive film j thus obtained werelaminated to obtain a composite film, laminated film adhesive k. Usingthis laminated film adhesive k, a chip (10 mm×10 mm; thickness: 0.5 mm)with gold bumps (area: 80 μm×80 μm each; space: 30 μm; height: 15 μm;the number of bumps: 288) was bonded to a Ni/Au-plated Cu circuitprinted substrate in the manner as shown below.

First, the adhesive film j (second adhesive layer) of this laminatedfilm adhesive k (12 mm×12 mm) was stuck to the Ni/Au-plated Cu circuitprinted substrate (electrode height: 20 μm; thickness: 0.8 mm) at 80° C.and 10 kgf/cm². Thereafter, the separator was peeled, and the chip wasfaced on the side of the adhesive film i (first adhesive layer), wherethe bumps of the chip were registered on the Ni/Au-plated Cu circuitprinted substrate (thickness: 0.8 mm). Then, heat and pressure wereapplied from above the chip under conditions of 180° C., 50 g/bump and20 seconds to effect main bonding.

Connection resistance after the main bonding was 18 mΩ at maximum perbump and 8 mΩ on the average, and insulation resistance was 10 ⁸Ω orabove. These values did not change even after 1,000-cycle treatment in athermal shock test made at −55 to 125° C., after a PCT (121° C., 2atmospheric pressure) made for 200 hours, and after 260° C. solder bathimmersion for 10 seconds, showing good connection reliability.

Example 8

50 g of phenoxy resin and 100 g of acrylic rubber (molecular weight:850,000) obtained by copolymerization of butyl acrylate (40 parts),ethyl acrylate (30 parts), acrylonitrile (30 parts) and glycidylmethacrylate (3 parts) were dissolved in 350 g of ethyl acetate toobtain a 30% solution.

Next, 350 g of liquid epoxy (epoxy equivalent weight: 185) containing amicrocapsular latent curing agent was added to this solution, followedby stirring, where fused silica (average particle diameter: 0.5 μm) inan amount of 60 parts by weight based on 100 parts by weight of theadhesive resin composition was dispersed to obtain a film coating fluid.

This film coating fluid was coated on a separator (silicone-treatedpolyethylene terephthalate film; thickness: 40 μm) by means of a rollcoater, followed by drying at 100° C. for 10 minutes to form an adhesivefilm m (thickness: 25 μm) corresponding to the first adhesive layer.This adhesive film m had a modulus of elasticity at 40° C. of 1,000 MPaafter curing as measured with a dynamic viscoelasticity measuringinstrument on only an adhesive resin composition from which the fusedsilica was removed.

An adhesive film n (thickness: 25 μm) corresponding to the secondadhesive layer was also formed in the same manner as the formation ofthe adhesive film m except that 5% by volume of conductive particlesobtained by forming Au layers on polystyrene cores (diameter: 5 μm) weredispersed in place of the dispersing of the fused silica. The resultantadhesive film n had a modulus of elasticity at 40° C. of 1,000 MPa.

Next, the adhesive film m and adhesive film n thus obtained werelaminated to obtain a. composite film, laminated film adhesive p. Usingthis laminated film adhesive p, a chip (10 mm×10 mm; thickness: 0.5 mm)with gold bumps (area: 80 μm×80 μm each; space: 30 μm; height: 15 μm;the number of bumps: 288) was bonded to a Ni/Au-plated Cu circuitprinted substrate in the manner as shown below.

First, the adhesive film n (second adhesive layer) of this laminatedfilm adhesive p (12 mm×12 mm) was stuck to the Ni/Au-plated Cu circuitprinted substrate (electrode height: 20 μm; thickness: 0.8 mm) at 80° C.and 10 kgf/cm². Thereafter, the separator was peeled, and the chip wasfaced on the side of the adhesive film m (first adhesive layer), wherethe bumps of the chip were registered on the Ni/Au-plated Cu circuitprinted substrate (thickness: 0.8 mm). Then, heat and pressure wereapplied from above the chip under conditions of 180° C., 50 g/bump and20 seconds to effect main bonding.

Connection resistance after the main bonding was 5 mΩ at maximum perbump and 1.5 mΩ on the average, and insulation resistance was 10⁸Ω orabove. These values did not change even after 1,000-cycle treatment in athermal shock test made at −55 to 125° C., after a PCT (121° C., 2atmospheric pressure) made for 200 hours, and after 260° C. solder bathimmersion for 10 seconds, showing good connection reliability.

Example 9

50 g of phenoxy resin and 125 g of acrylic rubber (molecular weight:850,000) obtained by copolymerization of butyl acrylate (40 parts),ethyl acrylate (30 parts), acrylonitrile (30 parts) and glycidylmethacrylate (3 parts) were dissolved in 400 g of ethyl acetate toobtain a 30% solution.

Next, 325 g of liquid epoxy (epoxy equivalent weight: 185) containing amicrocapsular latent curing agent was added to this solution, followedby stirring, where fused silica (average particle diameter: 0.5 μm) inan amount of 60 parts by weight based on 100 parts by weight of theadhesive resin composition was dispersed to obtain a film coating fluid.

This film coating fluid was coated on a separator (silicone-treatedpolyethylene terephthalate film; thickness: 25 μm) by means of a rollcoater, followed by drying at 100° C. for 10 minutes to form an adhesivefilm q (thickness: 25 μm) corresponding to the first adhesive layer.This adhesive film q had a modulus of elasticity at 40° C. of 800 Mpaafter curing as measured with a dynamic viscoelasticity measuringinstrument on only an adhesive resin composition from which the fusedsilica was removed.

An adhesive film r (thickness: 25 μm) corresponding to the secondadhesive layer was also formed in the same manner as the formation ofthe adhesive film q except that 2% by volume of nickel particles(diameter: 3 μm) were dispersed in place of the dispersing of the fusedsilica. The resultant adhesive film r had a modulus of elasticity at 40°C. of 800 MPa.

Next, the adhesive film q and adhesive film r thus obtained werelaminated to obtain a composite film, laminated film adhesive s.

Using this laminated film adhesive s, a bumpless chip (10 mm×10 mm;thickness: 0.5 mm; pad electrode: Al; pad diameter: 120 μm) was bondedto a Ni/Au-plated Cu circuit printed substrate on the circuit of whichNi/Au-plated Cu bumps (diameter: 100 μm; space: 50 μm; height: 15 μm;the number of bumps: 200) were formed, which was bonded in the manner asshown below.

First, the adhesive film r (second adhesive layer) of this laminatedfilm adhesive s (12 mm×12 mm) was stuck at 80° C. and 10 kgf/cm², to theNi/Au-plated Cu circuit printed substrate on which Ni/Au-plated Cu bumps(diameter: 100 μm; space: 50 μm; height: 15 μm; the number of bumps:200) were formed. Thereafter, the separator was peeled, and the chip wasfaced on the side of the adhesive film q (first adhesive layer), wherethe bumps of the chip were registered on the Ni/Au-plated Cu circuitprinted substrate (thickness: 0.8 mm). Then, heat and pressure wereapplied from above the chip under conditions of 180° C., 50 g/bump and20 seconds to effect main bonding.

Connection resistance after the main bonding was 8 mΩ at maximum perbump and 4 mΩ on the average, and insulation resistance was 10⁸Ω orabove. These values did not change even after 1,000-cycle treatment in athermal shock test made at −55 to 125° C., after a PCT (121° C., 2atmospheric pressure) made for 200 hours, and after 260° C. solder bathimmersion for 10 seconds, showing good connection reliability.

Example 10

195 g of phenoxy resin and 130 g of polyfunctional epoxy resin (epoxyequivalent weight: 212) were dissolved in 1,083 g of ethyl acetate toobtain a 30% solution.

Next, 325 g of liquid epoxy (epoxy equivalent weight: 185) containing amicrocapsular latent curing agent was added to this solution, followedby stirring, where 2% by volume of nickel particles (diameter: 5 μm) wasalso dispersed to obtain a film coating fluid.

This film coating fluid was coated on a separator (silicone-treatedpolyethylene terephthalate film; thickness: 40 μm) by means of a rollcoater, followed by drying at 100° C. for 10 minutes to form an adhesivefilm t (thickness: 25 μm) corresponding to the third adhesive layer.

This adhesive film t had a coefficient of thermal expansion of 45 ppm at30 to 100° C. after curing, a glass transition temperature of 150° C.and a modulus of elasticity at 40° C. of 2,600 MPa.

50 g of phenoxy resin and 100 g of acrylic rubber (molecular weight:850,000) obtained by copolymerization of butyl acrylate (40 parts),ethyl acrylate (20 parts), acrylonitrile (30 parts) and glycidylmethacrylate (3 parts) were also dissolved in 500 g of ethyl acetate toobtain a 30% solution.

Next, 350 g of liquid epoxy (epoxy equivalent weight: 185) containing amicrocapsular latent curing agent was added to this solution, followedby stirring, where 2% by volume of nickel particles (diameter: 5 μm) wasalso dispersed to obtain a film coating fluid.

This film coating fluid was coated on a separator (silicone-treatedpolyethylene terephthalate film; thickness: 40 μm) by means of a rollcoater, followed by drying at 100° C. for 10 minutes to form an adhesivefilm u (thickness: 25 μm) corresponding to the fourth adhesive layer.This adhesive film u had a coefficient of thermal expansion of 70 ppm at30 to 100° C. after curing, a glass transition temperature of 125° C.and a modulus of elasticity at 40° C. of 1,000 MPa.

Next, the adhesive film t and adhesive film u thus obtained werelaminated to obtain a composite film, laminated film adhesive v(thickness: 50 μm).

Then, using this laminated film adhesive v, a chip (size: 10 mm×10 mm;thickness: 0.55 mm) with gold bumps (height: 30 μm; the number of bumps:184) was bonded to a Ni/Au-plated Cu circuit printed substrate(electrode height: 20 μm; substrate thickness: 0.8 mm) in the manner asshown below.

First, the adhesive film u (fourth adhesive layer) of this laminatedfilm adhesive v (size: 12 mm×12 mm) was provisionally bonded to theNi/Au-plated Cu circuit printed substrate with the adhesive film u'sface set on the side of the printed substrate, under conditions of 60°C. and 0.5 MPa. After the step of provisional bonding, the bumps of thechip were registered on the Ni/Au-plated Cu circuit printed substrate,and the chip was mounted on the laminated film adhesive v. Subsequently,heat and pressure were applied from above the chip under conditions of180° C., 50 g/bump and 20 seconds to effect main bonding.

Connection resistance after the main bonding was 10 mΩ at maximum perbump and 2 mΩ on the average, and insulation resistance was 10⁸Ω orabove. These values did not change during continuous (in situ)measurement of resistance in the course of a 1,000-cycle thermal shocktest made at −55 to 125° C. and a PCT made for 500 hours at 110° C. and85% RH, showing a good connection reliability.

Example 11

195 g of phenoxy resin and 130 g of polyfunctional epoxy resin (epoxyequivalent weight: 212) were dissolved in 1,083 g of ethyl acetate toobtain a 30% solution.

Next, 325 g of liquid epoxy (epoxy equivalent weight: 185) containing amicrocapsular latent curing agent was added to this solution, followedby stirring, where fused silica (average particle diameter: 0.5 μm) inan amount of 20 parts by weight based on 100 parts by weight of theadhesive resin composition and also 2% by volume of nickel particles(diameter: 5 μm) were dispersed to obtain a film coating fluid.

This film coating fluid was coated on a separator (silicone-treatedpolyethylene terephthalate film; thickness: 40 μm) by means of a rollcoater, followed by drying at 100° C. for 10 minutes to form an adhesivefilm w (thickness: 25 μm) corresponding to the third adhesive layer.This adhesive film w had a coefficient of thermal expansion of 38 ppm at30 to 100° C. after curing, a glass transition temperature of 153° C.and a modulus of elasticity at 40° C. of 3,000 MPa.

50 g of phenoxy resin and 100 g of acrylic rubber (molecular weight:850,000) obtained by copolymerization of butyl acrylate (40 parts),ethyl acrylate (20 parts), acrylonitrile (30 parts) and glycidylmethacrylate (3 parts) were also dissolved in 500 g of ethyl acetate toobtain a 30% solution.

Next, 350 g of liquid epoxy (epoxy equivalent weight: 185) containing amicrocapsular latent curing agent was added to this solution, followedby stirring, where fused silica (average particle diameter: 0.5 μm) inan amount of 20 parts by weight based on 100 parts by weight of theadhesive resin composition and also 2% by volume of nickel particles(diameter: 5 μm) were dispersed to obtain a film coating fluid.

This film coating fluid was coated on a separator (silicone-treatedpolyethylene terephthalate film; thickness: 40 μm) by means of a rollcoater, followed by drying at 100° C. for 10 minutes to form an adhesivefilm x (thickness: 25 μm) corresponding to the fourth adhesive layer.This adhesive film x had a coefficient of thermal expansion of 60 ppm at30 to 100° C. after curing, a glass transition temperature of 127° C.and a modulus of elasticity at 40° C. of 1,400 MPa.

Next, the adhesive film w and adhesive film x thus obtained werelaminated to obtain a composite film, laminated film adhesive y(thickness: 50 μm).

Then, using this laminated film adhesive y, a chip (size: 10 mm×10 mm;thickness: 0.55 mm) with gold bumps (height: 30 μm; the number of bumps:184) was bonded to a Ni/Au-plated Cu circuit printed substrate(electrode height: 20 μm; substrate thickness: 0.8 mm) in the manner asshown below.

The adhesive film x (fourth adhesive layer) of this laminated filmadhesive y (size: 12 mm×12 mm) was provisionally bonded to theNi/Au-plated Cu circuit printed substrate with the adhesive film x'sface set on the side of the printed substrate, under conditions of 60°C. and 0.5 MPa. After the step of provisional bonding, the bumps of thechip were registered on the Ni/Au-plated Cu circuit printed substrate,and the chip was mounted on the laminated film adhesive y. Subsequently,heat and pressure were applied from above the chip under conditions of180° C., 50 g/bump and 20 seconds to effect main bonding.

Connection resistance after the main bonding was 10 mΩ at maximum perbump and 2 mΩ on the average, and insulation resistance was 10⁸Ω orabove. These values did not change during continuous (in situ)measurement of resistance in the course of a 1,000-cycle thermal shocktest made at −5.5 to 125° C. and a PCT made for 500 hours at 110° C. and85% RH, showing good connection reliability.

Comparative Example 1

Using the laminated film adhesive v obtained in Example 10, a chip(size: 10 mm×10 mm; thickness: 0.55 mm) with gold bumps (height: 30 μm;the number of bumps: 184) was bonded to a Ni/Au-plated Cu circuitprinted substrate (electrode height: 20 μm; substrate thickness: 0.8 mm)in the same manner as in Example 10 except that, in the presentComparative Example, the face of the adhesive film t (third adhesivelayer) of the laminated film adhesive v (size: 12 mm×12 mm) was set onthe side of the printed substrate.

Connection resistance after the main bonding was 10 mΩ at, maximum perbump and 2 mΩ on the average, and insulation resistance was 10⁸Ω orabove. However, these values changed in the course of a 500-cyclethermal shock test made at −55 to 125° C. and a PCT made for 300 hoursat 110° C. and 85% RH, resulting in faulty electrical conduction.

Comparative Example 2

195 g of phenoxy resin and 130 g of polyfunctional epoxy resin (epoxyequivalent weight: 212) were dissolved in 1,083 g of ethyl acetate toobtain a 30% solution.

Next, 325 g of liquid epoxy (epoxy equivalent weight: 185) containing amicrocapsular latent curing agent was added to this solution, followedby stirring, where 2% by volume of nickel particles (diameter: 5 μm) wasalso dispersed to obtain a film coating fluid.

This film coating fluid was coated on a separator (silicone-treatedpolyethylene terephthalate film; thickness: 40 μm) by means of a rollcoater, followed by drying at 100° C. for 10 minutes to form an adhesivefilm z of 50 μm thick. The adhesive film z had a coefficient of thermalexpansion of 45 ppm at 30 to 100° C. after curing, a glass transitiontemperature of 150° C. and a modulus of elasticity at 40° C. of 2,600MPa.

Next, using only the adhesive film z thus obtained, a chip (size: 10mm×10 mm; thickness: 0.55 mm) with gold bumps (height: 30 μm; the numberof bumps: 184) was bonded to a Ni/Au-plated Cu circuit printed substrate(electrode height: 20 μm; substrate thickness: 0.8 mm) in the manner asshown below.

First, the adhesive film z was provisionally bonded to the Ni/Au-platedCu circuit printed substrate under conditions of 60° C. and 0.5 MPa.After the step of provisional bonding, the bumps of the chip wereregistered on the Ni/Au-plated Cu circuit printed substrate, and thechip was mounted on the adhesive film z. Subsequently, heat and pressurewere applied from above the chip under conditions of 180° C., 50 g/bumpand 20 seconds to effect main bonding.

Connection resistance after the main bonding was 10 mΩ at maximum perbump and 3 mΩ on the average, and insulation resistance was 10⁸Ω orabove. However, these values changed after a 300-cycle thermal shocktest made at −55 to 125° C. and after 260° C. solder bath immersion for10 seconds, resulting in faulty electrical conduction. As a result ofcross-sectional observation of the bonded portions, separation of theadhesive film at its interface was observed at some part where thefaulty electrical conduction occurred.

Comparative Example 3

50 g of phenoxy resin and 100 g of acrylic rubber (molecular weight:850,000) obtained by copolymerization of butyl acrylate (40 parts),ethyl acrylate (20 parts), acrylonitrile (30 parts) and glycidylmethacrylate (3 parts) were also dissolved in 500 g of ethyl acetate toobtain a 30% solution.

Next, 350 g of liquid epoxy (epoxy equivalent weight: 185) containing amicrocapsular latent curing agent was added to this solution, followedby stirring, where 2% by volume of nickel particles (diameter: 5 μm) wasalso dispersed to obtain a film coating fluid.

This film coating fluid was coated on a separator (silicone-treatedpolyethylene terephthalate film; thickness: 40 μm) by means of a rollcoater, followed by drying at 100° C. for 10 minutes to form an adhesivefilm a of 25 μm thick. This adhesive film a had a coefficient of thermalexpansion of 60 ppm at 30 to 100° C. after curing, a glass transitiontemperature of 125° C. and a modulus of elasticity at 40° C. of 1,000MPa.

Next, using only the adhesive film α thus obtained, a chip (size: 10mm×10 mm; thickness: 0.55 mm) with gold bumps (height: 30 μm; the numberof bumps: 184) was bonded to a Ni/Au-plated Cu circuit printed substrate(electrode height: 20 μm; substrate thickness: 0.8 mm) in the manner asshown below.

First, the adhesive film α was provisionally bonded to the Ni/Au-platedCu circuit printed substrate under conditions of 60° C. and 0.5 MPa.After the step of provisional bonding, the bumps of the chip wereregistered on the Ni/Au-plated Cu circuit printed substrate, and thechip was mounted on the adhesive film α. Subsequently, heat and pressurewere applied from above the chip under conditions of 180° C., 50 g/bumpand 20 seconds to effect main bonding.

Connection resistance after the main bonding was 10 mΩ at maximum perbump and 2 mΩ on the average, and insulation resistance was 10⁸Ω orabove. However, these values changed during a high-temperature thermalshock test in a 30-cycle thermal shock test made at −55 to 125° C., sothat the electrical conduction became poor.

POSSIBILITY OF INDUSTRIAL APPLICATION

As described above, the present invention enables production of circuitboards that may cause neither increase in connection resistance atbonded portions nor separation at adhesive layers and have greatlyimproved in connection reliability.

1. A circuit board comprising: a first circuit member having a firstconnecting terminal; and a second circuit member having a secondconnecting terminal, the first connecting terminal and the secondconnecting terminal being disposed facing each other, and an adhesivebeing put between the first connecting terminal and the secondconnecting terminal which are facing each other, the first connectingterminal and the second connecting terminal disposed facing each otherbeing electrically interconnected by pressing, wherein the adhesivecomprises: one adhesive layer having a modulus of elasticity of from 100to 2000 MPa at 40° C. after curing; and another adhesive layer having amodulus of elasticity of from 500 to 5000 MPa at 40° C. after curing,which is higher than that of the one adhesive layer, the adhesive beingdisposed in such a way that the another adhesive layer is applied on theside of one of said circuit members which has a higher modulus ofelasticity than that of the other, and the one adhesive layer is appliedon the side of the other circuit member having a lower modulus ofelasticity.
 2. A circuit board comprising: a first circuit member havinga first connecting terminal; and a second circuit member having a secondconnecting terminal, the first connecting terminal and the secondconnecting terminal being disposed facing each other, and an adhesivebeing put between the first connecting terminal and the secondconnecting terminal which are facing each other, the first connectingterminal and the second connecting terminal disposed facing each otherbeing electrically interconnected by pressing, wherein the adhesivecomprises: one adhesive layer having a modulus of elasticity of from 100to 2000 MPa at 40° C. after curing; and another adhesive layer having amodulus of elasticity of from 500 to 5000 MPa at 40° C. after curing,which is higher than that of the one adhesive layer, the adhesive beingdisposed in such a way that the another adhesive layer is applied on theside of one of said circuit members which has a smaller coefficient ofthermal expansion than the other, and the one adhesive layer is appliedon the side of the other circuit member having a larger coefficient ofthermal expansion.
 3. A circuit board comprising: an inorganicinsulating substrate having a first connecting terminal; and an organicinsulating substrate having a second connecting terminal, the firstconnecting terminal and the second connecting terminal being disposedfacing each other, and an adhesive being put between the firstconnecting terminal and the second connecting terminal which are facingeach other, and the first connecting terminal and the second connectingterminal disposed facing each other being electrically interconnected bypressing, wherein the adhesive comprises: one adhesive layer having amodulus of elasticity of from 100 to 2000 MPa at 40° C. after curing;and another adhesive layer having a modulus of elasticity of from 500 to5000 MPa at 40° C. after curing, which is higher than that of the oneadhesive layer, the adhesive being disposed in such a way that theanother adhesive layer is applied on the side of the inorganicinsulating substrate, and the one adhesive layer is applied on the sideof the organic insulating substrate.
 4. A process for producing acircuit board, comprising steps of: (a) disposing a first circuit memberhaving a first connecting terminal and a second circuit member having asecond connecting terminal, in such a way that the first connectingterminal and the second connecting terminal face each other, saidcircuit members being so disposed that an adhesive is put between thefirst connecting terminal and the second connecting terminal which havebeen disposed facing each other, wherein the adhesive comprises: oneadhesive layer having a modulus of elasticity of from 100 to 2000 MPa at40° C. after curing; and another adhesive layer having a modulus ofelasticity of from 500 to 5000 MPa at 40° C. after curing, which ishigher then that of the one adhesive layer, the adhesive film beingdisposed in such a way that the another adhesive layer is applied on theside of one of said circuit members which has a higher modulus ofelasticity than the other, and the one adhesive layer is applied on theside of the other circuit member having a lower modulus of elasticity;and (b) pressing the resultant circuit members to electricallyinterconnect the first connecting terminal and the second connectingterminal disposed facing each other.
 5. A process for producing acircuit board, comprising steps of: (a) disposing a first circuit memberhaving a first connecting terminal and a second circuit member having asecond connecting terminal, in such a way that the first connectingterminal and the second connecting terminal face each other, saidcircuit members being so disposed that an adhesive is put between thefirst connecting terminal and the second connecting terminal which havebeen disposed facing each other, wherein the adhesive comprises: oneadhesive layer having a modulus of elasticity of from 100 to 2000 MPa at40° C. after curing; and another adhesive layer having a modulus ofelasticity of from 500 to 5000 MPa at 40° C., after curing, which ishigher than that of the one adhesive layer, the adhesive being disposedin such a way that the another adhesive layer is applied on the side ofone of said circuit members which has a smaller coefficient of thermalexpansion than the other, and the one adhesive layer is applied on theside of the other circuit member having a larger coefficient of thermalexpansion; and (b) pressing the resultant circuit members toelectrically interconnect the first connecting terminal and the secondconnecting terminal disposed facing each other.
 6. A process forproducing a circuit board, comprising steps of: (a) disposing aninorganic insulating substrate having a first connecting terminal and anorganic insulating substrate having a second connecting terminal, insuch a way that the first connecting terminal and the second connectingterminal face each other, said insulating substrates being so disposedthat an adhesive is put between the first connecting terminal and thesecond connecting terminal which have been disposed facing each other,wherein the adhesive comprises: one adhesive layer having a modulus ofelasticity of from 100 to 2000 MPa at 40° C. after curing; and anotheradhesive layer having a modulus of elasticity of from 500 to 5000 MPa at40° C. after curing, which is higher than that of the one adhesivelayer, the adhesive film being disposed in such a way that the anotheradhesive layer is applied on the side of the inorganic insulatingsubstrate, and the one adhesive layer is applied on the side of theorganic insulating substrate; and (b) pressing the resultant insulatingsubstrates to electrically interconnect the first connecting terminaland the second connecting terminal disposed facing each other.